home • about • essential guide • picture of the day • thunderblogs • news • multimedia • predictions • products • get involved • contact

news and views

Saturn's icy moon Dione may have much in common with its active sibling Enceladus, new research using Cassini spacecraft data has revealed.

Paul Schenk of the Lunar and Planetary Institute and Jeff Moore of NASA's Ames Research Center modelled Dione's surface using digital elevation models (DEMs). Their results indicate volcanism has been a major force in shaping Dione's surface.

"We don't see giant shield volcanoes belching lavas," says Schenk. "Instead we see smooth plains with low crater densities."

These plains are the hallmark of cryovolcanism, which manifests itself as an outpouring of icy liquids from a moon's interior.

How it works

The DEMs used by Schenk and Moore reveal Dione's cryovolcanic plains to be higher than the surrounding terrain, suggesting they may have been emplaced in a high viscosity flow similar to terrestrial glaciers sometime within the last 2 billion to 4 billion years.

Cryovolcanism requires a heat source to drive liquids to the surface. At present the mechanism for this heat engine is not fully understood but the two leading contenders are radioactive decay and gravitational flexing.

"As far as the source of the heat, well that's the big question. It is clear that some of the craters (on Dione) have been severely modified by high heat flow, not unlike parts of Enceladus. Perhaps these satellites (Dione and Enceladus) were very hot to begin with and had continued tidal heating to keep them warm," Schenk told SPACE.com.

This tidal heating of these moons interiors would be caused by Saturn's strong gravitational pull as well as help from Dione and Enceladus' orbital resonance; Enceladus completes two orbits of Saturn for every one achieved by Dione.

Full story here
__________________________

See our TPOD Enceladus Plumes Explained?

home   •   updates   •   news and views   •  picture of the day   •   resources  •   team   •   a role for you   •  contact us